Digital Public Defence: Knut Erik Mjaaland Knut Erik Mjaaland at Institute of Clinical Medicine will be defending the thesis “The anterior approach in total hip arthroplasty. Assessment of the approach and comparison to other approaches” for the degree of PhD (Philosophiae Doctor).

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The public defence will be held as a video conference over Zoom.

The defence will follow regular procedure as far as possible, hence it will be open to the public and the audience can ask ex auditorio questions when invited to do so.

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Due to copyright reasons, an electronic copy of the thesis must be ordered from the faculty. In order for the faculty to have time to process the order, it must be received by the faculty no later than 2 days prior to the public defence. Orders received later than 2 days before the defence will not be processed. Inquiries regarding the thesis after the public defence must be addressed to the candidate.

Digital Trial Lecture – time and place

See Digital Trial Lecture.

Adjudication committee

  • First opponent: Professor Michael Mørk Petersen, University of Copenhagen, Denmark
  • Second opponent: Professor Ville Mattila, Tampere University Hospital, Finland
  • Third member and chair of the evaluation committee: Professor Hilde Berner Hammer, University of Oslo

Chair of the Defence

Professor Trygve Holmøy, University of Oslo

Principal Supervisor

Professor II Lars Nordsletten, University of Oslo


Total hip arthroplasty is a well-established and reliable treatment in restoring function and relieving pain in end-stage osteoarthritis of the hip. Different surgical approaches can be used. The most used are the posterior approach, where the external rotators of the hip are released, and the direct lateral approach where the gluteus minimus and the anterior part of the gluteus medius are released. The direct anterior approach has increasing popularity. The approach utilizes a muscle and nerve neutral interval and is advertised as “minimally invasive surgery (MIS)”. The aim of this thesis was to evaluate the anterior approach and compare it to other approaches.

The thesis consists of two papers from a randomized trial with two-year follow-up comparing the anterior (84 patients) and direct lateral approach (80 patients) and one paper with data from the Norwegian Arthroplasty Register including 21,860 hips.

The patients operated using the anterior approach had higher postoperative CK values but lower levels of pain and required less pain medication than those operated using the direct lateral approach.

No clinically important differences were found between the approaches at any time point in any of the outcome measures except the Trendelenburg test which was positive in a significantly higher number of patients in the direct lateral group at all time points, indicating poor gluteal muscle function. Irrespective or approach used, patients who were Trendelenburg test positive had significantly worse outcome than those who were negative.

No difference was found in 2 and 5-year implant survival between the approaches. Relative risk of revision due to infection was double for the direct lateral approach and the posterior approach had double risk of revision due to dislocation compared to the other approaches.

Overall, the thesis indicate that the anterior approach is a good approach to use in total hip arthroplasty.

Additional information

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Published Oct. 22, 2021 11:33 AM - Last modified Nov. 4, 2021 12:52 PM